Wind energy components are massive in scale and continue to grow larger. For the wind energy companies that build the turbines and towers and for the transportation companies that move the equipment across the continent, the components’ sheer size does present some challenges. Project developers and their consultants have to turn to technology to model the vehicle swept paths and demonstrate safe clearances to freeway overpasses, roadside signs, light standards and site access roads along their proposed routes. According to Alex Lockard, civil engineer at Vestas American Wind Technology Inc., there are two pieces of equipment the original equipment manufacturers worry about most.
“We have three main loads in the wind energy industry: the blades, the tower sections and the nacelle,” says Lockard. “People don’t generally model the hub and nacelle, but the blade and the tower sections govern the roadway design. We know that the tip of the blade overhangs quite far at the back end of the trailer. It swings way out as you go through tight radius turns, and it can hit all kinds of things like light poles, utility poles, trees and structures. All these things have to be checked.”
Trucking companies, such as Lone Star Transportation, are responsible for obtaining permits from the local Departments of Transportation when moving large loads across state lines. Sometimes, additional permits are required to use county or municipal district roads. The governing bodies want to know if there are any hazards or dangers in moving the load through their jurisdiction. Trucking companies complete an initial transport survey, which is a run-through of the roadway to identify which objects might be a problem.
“Wind energy is a whole different segment of specialized transport as far as the volumes and the site roads go,” comments Brandon Brown, a senior project manager for Lone Star Transportation. “[Y]ou could definitely say that the components are getting bigger.”
In 2012, Vestas and Lone Star Transportation teamed up on wind farm projects in Vermont and New York. A project in Lowell, Vt., called the Kingdom Community Wind Farm, consisted of 21 turbines on a ridgeline of the Lowell Mountain Range. Working together with Vermont Electric Co-op and Green Mountain Power (GMP), Vestas supplied the blades and towers for the project. However, getting the equipment to the top of the mountain was an engineering challenge.
“One of the constraints we had was the one-and-a-half-mile road we had to travel up to the ridgeline,” says Charles Pughe, project manager for GMP on the Kingdom Community project. “It was very steep, sometimes up in the 15 percent range, so we had traction issues in trying to get the equipment up to the site. The tower sections and nacelles were towed when they went up the hill.”
Pughe continues, “We had an articulated tractor towing the prime movers going up the mountain. Most of the tower sections were on non-steerable low-boys. One of the tricks was to figure out what the turns were going to be like. When the tractor was pulling the prime mover through the corners, the trailer wasn’t tracking directly. It’s like being on water skis – when the boat is pulling you, you don’t ski directly behind it. The tractor was taking the corner a little wider than the truck, and it was difficult to figure that out ahead of time as the pitch of the roadway affected how far out in the corner the tractor would end up.”
“The Kingdom Community project was similar to any other wind farm project. [Companies] don’t want to spend money on roads and build them to what you need, so you have to make things happen in a field setting,” adds Lone Star’s Brown. “That’s a common issue in the wind industry – site roads. It’s a huge cost, so the less they build, the more money they can make. It increases the likelihood they can make a project happen.
“In those cases, you rely on experience, and because we have done so many [wind farm projects], our guys in the field know what they need,” he adds. “There are road specifications detailed into the contract that we had input previously, so we know what is required to deliver the turbines to their final destination.”
Several months prior to moving the blades and tower sections, in February 2012, Vestas and Lone Star worked together with Transoft Solutions to perform a number of vehicle tests in a Vestas works yard in Brighton, Colo. The Vestas project team wanted to know how the wind energy equipment would move when making specific turns. A driving course was built to replicate the critical roadway geometry of the planned access road for the complex terrain required in the Kingdom Community project. GPS coordinates from key points on the truck, trailer and loaded blade were recorded. Using software called AutoTURN, the swept path of the simulated vehicle matched the swept path of the field test vehicle accurately, with variances consistently less than 30 cm.
“We took some of the geometry from the Kingdom Community Wind site access road designs,” says Lockard. “I asked the customer on that project, ‘What curves are you most concerned about not being able to make?’ The reason the geometry was so critical for this project is that they had a ridgetop, mountain-side project. They were going to have to blast rock out of the way to construct the roads. Every square inch mattered to them and to us from a sustainability standpoint.”
“Our biggest concern was getting the blades up [to the site], because they were 180 feet long,” Pughe says. “We had a lot of switchback-type roads constructed to gain the elevation because we were trying to stay within a relatively small corridor.”
“For the Kingdom project, GMP did upsize the turbines in the spring of 2011, after the civil engineering and associated permit applications were complete,” Pughe adds. “We used [the software] to verify that the roads would still work for the blades and the tower sections. One issue with doing this was that the blade trailer to transport the V112 blades hadn’t actually been built yet. That is why it was so critical to have Vestas do the mock-up in Brighton once an actual trailer was available.”
The Colorado field test served several purposes: It helped Vestas show GMP that the road geometry would work, validated the modeling software and helped Lockard gain some peace-of-mind that the blades would not get damaged on the way up the steep and twisting roads.
“We made virtually no modifications to the road going up the hill based on our modeling of it, except filling in some ditches and giving ourselves some extra room in the corners by cutting down a tree or two,” Pughe explains. “We did that just to be safe, and we didn’t want to find out after we bumped a blade into a tree.”
The Marble River wind energy project, located in Clinton County, N.Y., was also a successful collaboration for EDP Renewables, Vestas and Lone Star. Plans called for 70 Vestas V112 3-MW wind turbines to be installed across two upstate New York towns (16 units in Ellenburg and 54 in Clinton). The 492-foot wind towers are the largest ever approved in the state of New York. The wind farm, which became operational in November 2012, is capable of producing up to 216 MW of power.
Just before the construction phase of the project was about to start, EDP Renewables had decided to change the size of turbines to maximize the amount of energy the wind farm could generate. Before they could finalize the deal, EDP Renewables and Vestas had to make sure the larger blades could still make it through all the roadways’ curves. Vestas turned to AutoTURN to answer the key questions.
Transoft engineers helped Vestas with analysis of some of the key road geometry. “It was critical to us in the sales phase of that project,” says Lockard. “I was being asked, ‘Will the geometry work?’ The project was designed not for Vestas turbines but a competitor turbine with different-length blades and different-diameter tower sections. The client had done the original civil engineering work for a different turbine, different manufacturer, different length, different everything. It was a good win for us, and my role was to make sure we could do it safely.”
For Pughe, return on investment was an important consideration. If it was possible to transport the bigger turbines up to the site, he felt it would pay off in the long term.
“We were looking to maximize the size and generating capacity of the wind turbines on the site,” says Pughe. “One of the reasons we went with the Vestas V112s, which had the extra big blade, was we found that would be the highest yield for our footprint of construction. We would get the most energy out of them. We ended up choosing the biggest machines that were available to us at the time, knowing that it would be difficult construction to get it up there. We felt it would be worth it in the end because [the site] would yield greater energy output for the amount of construction we had to do.”
There were considerable time constraints to look at all the variables on the Marble River project. Using the software, Vestas and Transoft evaluated nearly 50 intersections, along with the site roads, for clearance issues. Over a four-week period, they collaborated to deliver the information that Lockard and his team needed to move the project forward. w
Marketplace: Transportation & Logistics
Technology Enables Better Turbine Transport
By Chris Johns
Increasingly, developers are turning to technology to model the best routes for delivering turbine components quickly and efficiently.
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